Nuts and Nut Butters:

Research shows that dieters who ate foods containing monounsaturated fats (like nuts and nut butters) lost more belly fat than those who ate the same number of calories with less of the fats. No matter what your favorite nut or nut butter is, it's a great flat-belly choice since they all contain these healthy fats!

The key is keeping your portions in check, so stick to 1/4 cup for nuts and a tablespoon for nut butters.

Mushrooms:

Mushrooms are the only natural plant source of Vitamin D. Insufficient levels of Vitamin D have been linked to higher levels of belly fat. Look for mushrooms that are labeled as being exposed to ultraviolet light, as those will have even higher levels of vitamin D.

Mushrooms add a great meaty texture to everything from a salad to a pasta dish!

Air-Popped Popcorn:

Popcorn is a great flat-belly snack as long as you choose the air-popped version—you can eat a 3-cup portion for only 100 calories! Not only that, but popcorn is also a whole grain, and studies show that people who eat whole grains have less belly fat than those who eat refined grains.

Beans:

Beans are a great belly-flattening food because research shows that bean eaters weigh less and have slimmer waistlines. Perhaps this is because they are relatively low in calories but high in filling fiber!

If you are afraid that the fiber in beans will cause gas and bloating, just be sure to increase the amount of beans you eat gradually and to drink plenty of water to avoid those issues.

Quinoa:

Quinoa is a whole grain like popcorn, which makes it a great tummy trimmer. As an added bonus, quinoa is the only grain that is also a complete protein and protein helps us feel fuller longer, which can help you reach your flat-belly goals sooner!

Enjoy it hot with fruit as a breakfast option or cold as a part of a salad for lunch or dinner.

Fruits and Veggies:

All fruits and veggies are great flat-belly foods as most of them are 80-90% water. This means they are high in nutrients, but low in calories. Plus, the fiber they contain helps you feel fuller longer, so you'll lose fat without feeling hungry all the time!

My favorites for the summer include watermelon, tomatoes, and leafy greens.